Gazzaniga is the director of the SAGE Center for the Study of Mind at UCSB. His book begins with a historical overview of various speculations on consciousness over the centuries, starting with the ancient Greeks and continuing through Freud and Schopenhauer, before ending with Gazzaniga’s own opinions on the nature of consciousness. Many of history’s earlier claims about consciousness are still relevant as they lay the foundations for modern controversies that still divide the neuroscience community today. Among the prominent theories Gazzaniga reviews are Descartes’ mind/body dualism, Locke’s tabula rasa (blank slate) formulation, which led to Skinner’s behaviorism, and Hume’s chains of perception. John von Neumann was to add to speculations on the workings of neural networks by proposing the idea of parallel organization, where different groups of neurons could run independently and simultaneously. Chomsky supposedly dealt behaviorism a fatal blow with his ideas on a universal grammar, innate in all humans. Gazzaniga and his mentor Robert Sperry were to conduct research on humans whose brains had been surgically split to ease epileptic seizures. Sperry recounted, “everything we have seen so far indicates that the surgery has left these people with two separate minds, that is, two separate spheres of consciousness.” This research laid waste to the idea that consciousness was located in any particular area of the brain or even, in fact, that each human had one unique conscious ‘self’ at all. Sperry felt that “consciousness may have real operational value, that is more than merely an overtone, a by-product, epiphenomenon, or a metaphysical parallel of the objective process.” Sperry leaned towards the idea of emergentism: that “consciousness emerges from unconscious matter once that matter achieves a certain level of complexity or organization.” This is in contrast to the other major materialist idea of panpsychism: that all matter has some type of consciousness within it, albeit with a wide range of both scale and scope. All modern consciousness researchers strive to get at what David Chalmers has labeled “the hard problem” or Thomas Nagel has described as “what it is like” to be something, subjectively. Nagel stated, “an organism has conscious mental states if and only if there is something that it is like to be that organism—something it is like for the organism.” These subjective characteristics of experience have sometimes been referred to as qualia. On the other hand, the philosopher Daniel Dennett disagreed that subjective experience was even a scientific problem/issue. He suggested it was all an ultra-realistic illusion and that the sensation of “‘having an experience’ is beyond the realm of the objective” and thus beyond the realm of science. Gazzaniga’s effort in the rest of his book aims to refute this “new dualism” and tries to fit consciousness within the modern research paradigm of the material brain.
Gazzaniga describes the brain as being separated by independent neural modules. “Modules are specialized and frequently localized networks of neurons that serve a specific function…. The perks of brain modularity are that it saves energy when resources are scarce, allows for specialized parallel cognitive processing when time is limited, makes it easier to alter functionality when new survival pressures arise, and allows us to learn a variety of new skills.” On top of this modular structure of the brain is a layered architecture. “Each layer in a system operates independently because each layer has its own specific protocols, the set of rules or specifications that stipulate the allowed interfaces, or interactions, both within and between layers.” This layered system allowed humans to evolve from simpler life forms, while keeping their lower-level structures and building on top of them, rather than beginning a unified functioning structure from scratch. Therefore, many of our bodily functions, from metabolism to replication, are formed using the same core-processes as that of simpler forms of life, such as bacteria, since we all share the same genomic sequences. This layered architecture evolved because it limits the effects of localized malfunctions, making repair or replacement easier, and making for a more robust, if less efficient, system. “Because each layer can provide a wide range of diverse functions, the system has greater flexibility as a whole, giving it a great advantage when facing a changing environment. This type of layout is ideal in an evolutionary sense because the number of vulnerabilities in the system is limited, while the opportunities for diversification are abundant.” Neural redundancy becomes a feature, not a bug, of this system. Therefore, “there may not be a specific modular hierarchy that allows consciousness to manifest itself in one way or another. Specific modules work relatively independently and, rather than being a neatly ordered queue of modular processing, the contents of our conscious experience may be the result of some kind of competition: some processing takes hold of your conscious landscape at a given moment in time…. The multitude of conscious-producing modules simply diversifies your conscious portfolio…. The modular brain makes consciousness resilient because of the plethora of possible paths that can lead to a conscious moment…. The brain operates in a modular fashion, but it also suggests that independent modules can each produce a unique form of consciousness.”
Gazzaniga feels that consciousness research could learn a great deal from quantum physics, particularly the idea of complementarity: that matter, such as electrons, can have both particle-like and wavelike properties. There is both the macro-world of Newtonian physics and the micro-world of quantum physics, in which the same matter behaves by different laws, all at once. Particular to quantum mechanics is the idea that the observer matters. He affects the system by his very observation of it. Any measurement requires an observer who is separate from the object measured. “The measurement itself may be precise and objective, but the process of measurement is subjective.” Gazzaniga suggests that “human consciousness was way too high a layer in the architecture of all living organisms to put the epistemic cut between the observer and the observed, between the subjective experience and the event itself.” The key to consciousness might begin with the difference between the living and the lifeless. He quotes Howard Pattee, “I have taken the point of view that the question of what constitutes an observation in quantum mechanics must arise long before we reach the complexity of the brain. In fact, I propose…. that the gap between quantum and classical behavior is inherent in the distinction between inanimate and living matter…. Our models of living organisms will never eliminate the distinction between the self and the universe, because life began with this separation and evolution requires it…. This is a universal and irreducible complementarity. Neither model can derive the other or be reduced to the other.” Gazzaniga suggests that these “two complementary modes of behavior, two levels of description are inherent in life itself, were present at the origins of life, have been conserved by evolution, and continue to be necessary for differentiating subjective experience from the event itself.” William James had suggested the idea of polyzoism: that “every brain-cell has its own individual consciousness, which no other cell knows anything about, all individual consciousness being ‘ejective’ to each other.” Gazzaniga suggests that each cell has a very rudimentary conception of the subjective ‘self’, built on the fact that each cell has semiotic closure, the key to independent living systems present in all cells. He continues, “neural circuits are structures with a double life: they carry symbolic information, which is subject to arbitrary rules, yet they possess a material structure that is subject to the laws of physics.” Gazzaniga suggests that consciousness is the linkage of independent neural modules that span across time and memory. “Each mental event is managed by brain modules that possess the capacity to make us conscious of the results of their processing…. Those single bursts of processing parade one after another, seamlessly linked by time…. Our smoothly flowing consciousness is itself an illusion. In reality it is made up of cognitive bubbles linked by subcortical “feeling” bubbles, stitched together by our brain in time…. Consciousness is inherent throughout the brain.”
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